A Strange Truncation of the Briffa MXD Series

Post-1960 values of the Briffa MXD series are deleted from the IPCC TAR multiproxy spaghetti graph. These values trend downward in the original citation (Briffa [2000], see Figure 5), where post-1960 values are shown. The effect of deleting the post-1960 values of the Briffa MXD series is to make the reconstructions more "similar". The truncation is not documented in IPCC TAR. In most cases, people would ask: who at IPCC truncated this series? why did they do so? who approved the truncation? what process was involved in approving the truncation? I’ve gone through a laborious process to calculate what the untruncated IPCC spaghetti graph would look like and show the calculations here.

If nitrogen is to blame, ring density will be lower, but ring width would increase. Is there any indication for that? I remember that tree rings in Belgium have a growth spurt in the last halve century, probably by more CO2, but maybe also by more nitrogen in a densily populated and industrialised country. May be solved by a density/ring width comparison…

It’s a good point, but you need to show the bottom line more quickly. It’s pretty tedious to wade through all this stuff to get the result. Why not just have a “with and without” picture right at the beginning?

Yeah. I agree. Some promotion (of self or of overpuffing the importance of work) is common in 30something ambitious academic turks. But this stuff is just a tendentious mess. And listening to all the rationales and the lack of intellectual vibrancy and curiousity…shows me a field of arguers, not discoverers.

[…] To my knowledge, no one noticed or reported this truncation until my Climate Audit post in 2005 here. The deletion of the decline was repeated in the 2007 Assessment Report First Order and Second […]

[…] This “apparent” truncation of data had been spotted and discussed at Climate Audit as far back as 2005: Post-1960 values of the Briffa MXD series are deleted from the IPCC TAR multiproxy spaghetti graph. These values trend downward in the original citation (Briffa [2000], see Figure 5), where post-1960 values are shown. The effect of deleting the post-1960 values of the Briffa MXD series is to make the reconstructions more “similar”. The truncation is not documented in IPCC TAR. In most cases, people would ask: who at IPCC truncated this series? why did they do so? who approved the truncation? what process was involved in approving the truncation? (Climate Audit, A Strange Truncation of the Briffa MXD Series) […]

[…] relatively favorably in my May 2005 post in which I first drew attention to the “trick” A Strange Truncation of the Briffa MXD Series (see image below). I had no complaint with the original Briffa articles – it was the IPCC […]

[…] The truncation of the Briffa reconstruction in IPCC TAR was first reported at CA in May 2005 here; the construction of the smooth in the IPCC diagram was dissected by Jean S and UC and reported at […]

[…] 20th century downturn in the Briffa 2001 graphic in the IPCC graphic, that I observed some time ago here. Since data truncation is in the news, I was going to update the graphic in this post to better show […]

[…] and this finding shows an inverse relation with temperature to tree height. Maybe this is why Briffa had to truncate uncooperative tree ring data post 1960 and Mike’s Nature trick was used to “hide the […]

[…] and this finding shows an inverse relation with temperature to tree height. Maybe this is why Briffa had to truncate uncooperative tree ring data post 1960 and Mike’s Nature trick was used to “hide the […]

[…] and this finding shows an inverse relation with temperature to tree height. Maybe this is why Briffa had to truncate uncooperative tree ring data post 1960 and Mike’s Nature trick was used to “hide the […]